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| Titel |
Sea-surface salinity variations in the northern Caribbean Sea across the Mid-Pleistocene Transition |
| VerfasserIn |
S. Sepulcre, L. Vidal, K. Tachikawa, F. Rostek, E. Bard |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 1 ; Nr. 7, no. 1 (2011-02-11), S.75-90 |
| Datensatznummer |
250004398
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| Publikation (Nr.) |
 copernicus.org/cp-7-75-2011.pdf |
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| Zusammenfassung |
| By reconstructing past hydrologic variations in the Northern Caribbean Sea
and their influence on the stability of the Atlantic Meridional Overturning
Circulation (AMOC) during the last 940 ka, we seek to document climate
changes in this tropical area in response to the Mid-Pleistocene Transition
(MPT). Using core MD03-2628, we estimated past changes in sea surface
salinity (SSS) using Δδ18O, the difference between the
modern, and the past δ18O of seawater (obtained by combining
alkenone thermometer data with the δ18O of the planktonic
foraminifera Globigerinoides rube (white) and corrected for ice-sheet volume effects). Today,
the lowest SSS values in the area studied are associated with the
northernmost location of the Inter-Tropical Convergence Zone (ITCZ). The
Δδ18O record obtained from core MD03-2628 exhibits
glacial/interglacial cyclicity with higher values during all glacial periods
spanning the last 940 ka, indicating increased SSS. A long-term trend was
also observed in the Δδ18O values that exhibited a
shift toward lower values for interglacial periods during the last 450 ka,
as compared to interglacial stages older than 650 ka. A rise in SSS during
glacial stages may be related to the southernmost location of the ITCZ,
which is induced by a steeper cross-equator temperature gradient and
associated with reduced northward cross-equatorial oceanic transport.
Therefore, the results suggest a permanent link between the tropical
salinity budget and the AMOC during the last 940 ka. Following the MPT,
lower salinities during the last five interglacial stages indicated a
northernmost ITCZ location that was forced by changes in the cross-equator
temperature gradient and that was associated with the poleward position of
Southern Oceanic Fronts that amplify the transport of heat and moisture to
the North Atlantic. These processes may have contributed to the
amplification of the climate cycles that followed the MPT. |
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